1. Field of the Invention
The present invention relates to a method and apparatus for transmitting data in a radio communication network. More particularly, the present invention relates to a method and apparatus for a User Equipment (UE) to transmit data when the UE that is in an idle mode accesses an evolved-Node B (eNB) for transmission of a small amount of data.
2. Description of the Related Art
In general, Universal Mobile Telecommunications System (UMTS) is a 3rd Generation (3G) communication system that is based on Global System for Mobile communications (GSM) and General Packet Radio Services (GPRS), and that uses Wideband Code Division Multiple Access (WCDMA). The 3rd Generation Partnership Project (3GPP), which works for standardization of UMTS, has proposed Evolved Packet System (EPS) that corresponds to a next generation communication system of UMTS such as a Long Term Evolution (LTE) system, for embodying a high-speed packet-based communication.
FIG. 1 illustrates a configuration of an LTE radio communication network according to the related art.
As shown in FIG. 1, the radio communication network may include an eNB 102, a Mobility Management Entity (MME) 104, a Serving GateWay (S-GW) 106, a Packet Data Network GateWay (PDN-GW) 108, and a UE 100.
The eNB 102 may be an eNB that manages a macrocell. Here, for ease of description, the terms “macrocell” and “eNB” may be used interchangeably, although the macrocell is a cell in a general cellular system and the eNB 102 is an eNB that manages and controls the macrocell.
The eNB 102 may be connected to the UE 100 through a radio channel, and may control a radio resource. For example, the eNB 102 may generate control information required in the macrocell as system information and broadcast the system information, or may allocate radio resources so as to perform, with the UE 100, transmission and reception of data or control information. In addition, the eNB 102 may collect information of channel measurement results of a current cell and adjacent cells from the UE 100 so as to determine a handover, and may command the UE 100 to perform the handover. Accordingly, the eNB 102 may include a control protocol, such as a radio resource protocol associated with radio resource management and the like.
The MME 104 may manage a mobility of the UE 100 that is in an idle mode, and may select the PDN-GW 108 and the S-GW 106 for data transmission of the UE 100. In addition, the MME 104 may perform functions associated with roaming and authentication of the UE 100. The MME 104 may process a bearer signal occurring from the UE 100.
The S-GW 106 may function as a mobile anchor when a handover occurs between eNBs or movement occurs between 3GPP radio networks. The PDN-GW 108 may allocate an Internet Protocol (IP) address of the UE 100, may perform connecting of a core network and a packet data network, and may function as a mobile anchor when movement occurs between a 3GPP radio network and a non-3GPP radio network. Also, the PDN-GW 108 may determine a bearer band to be provided to a subscriber, and may perform forwarding and routing of packet data.
When the UE 100 accesses the eNB 102, the UE 100 may access an Internet network 110 through use of a data transmission path 110 that goes through the eNB 102, the S-GW 106, and the PDN-GW 108. To implement the above, a related signaling may be transferred via a path that goes through the UE 100, the eNB 102, the MME 104, the S-GW 106, and the PDN-GW 108.
FIG. 2 illustrates a process where a UE that is in an idle mode transmits data in an LTE radio communication network according to the related art.
Referring to FIG. 2, a UE 200 that is in an idle mode may transmit a Radio Resource Control (RRC) connection request message to an eNB 202 in operation 210. The RRC connection request message may include an Identifier (ID) of the UE 200, that is, a System Architecture Evolution (SAE) Temporary Mobile Subscriber Identifier (S-TMSI). The eNB 202 may transmit an RRC connection setup message to the UE 200 in operation 212, and the UE 200 may transfer an RRC connection setup complete message to the eNB 202 in operation 214. The RRC connection setup complete message may include a Non-Access Stratum (NAS) message that the UE 200 transmits to an MME 204. The NAS message may be a message to request a service from an NAS layer that connects the UE 200 and the MME 204 so as to switch the UE 200 from an idle mode to an active mode.
The eNB 202 may notify of the connection of the UE 200 to the MME 204 through INITIAL UE MESSAGE in operation 216, and may transmit the NAS message received in operation 214 to the MME 204.
In operation 218, the MME 204 may transmit, to the eNB 202, security information of the UE 200, information associated with a data bearer of the UE 200, information associated with an S-GW 206 to which the eNB 202 is to transmit data received from the UE 200, that is, S1-U UL information (uplink bearer GPRS Tunneling Protocol (GTP) Tunnel ID (TEID)), an IP address of the S-GW 206, and context information of the UE 200 such as mobility management information of the UE 200, through use of an INITIAL CONTEXT SETUP REQUEST message.
In operations 220 and 222, the eNB 202 may set an Access Stratum (AS) security and a data bearer between the UE 200 and the eNB 202 in conjunction with the UE 200 based on the context information of the UE 200 received in operation 218, through use of an RRC connection reconfiguration message and an RRC connection reconfiguration complete message.
In operation 224, the eNB 202 may inform the MME 204 that the context of the UE 200 and the data bearer are successfully set, through use of an INITIAL CONTEXT SETUP RESPONSE message, and may also transmit information associated with the eNB 202 required for transmitting data from the S-GW 206 to the UE 200, that is, S1-U DL information of the UE 200 (downlink bearer GTP TEID and an IP address of the eNB 202). That is, the MME 204 may transmit, to the S-GW 206, the downlink bearer GTP TEID of the UE 200 and the IP address of the eNB 202 received from the eNB 202 in operation 224, through use of an Update Bearer Request message in operation 226, and may receive a response message from the S-GW 206 through use of an Update Bearer Response message in operation 228.
Through the processes as described in the foregoing, the UE 200 may transmit data after operation 222, and the data transmitted from the UE 200 may be transmitted to an Internet network via the eNB 202, the S-GW 206, and the PDN-GW 208 in operation 230.
As shown in FIG. 2, to transmit data, the UE 200 that is in an idle mode may require ten signalings that are transmitted and received in operations 210 through 228. This condition is equivalently applied even when a significantly small amount of data is transmitted, such as an alarm message, a power consumption measurement results reporting message, and the like. Also, when the amount of data is significantly small, the signaling overhead necessary for support of the transmitted and received data may be even greater than the amount of data to be transmitted. Accordingly, there is a need for a method to overcome these drawbacks.